In the construction field there are a number of different types of external walls, such as stud walls of wood or steel and massive walls of, for example, concrete.
For exterior sealing for the purpose of preventing intrusion of water in a building foundation and for the provision of a wind shield, one solution is disclosed in U.S. Pat. No. 4,700,512. The document discloses a flexible membrane adapted for exterior sealing of a masonry building foundation. Yet, the membrane allows passage of air, admitting dehydration of the humidity that is naturally found in the building. Another solution to the same problem is found in U.S. Pat. No. 6,401,401 B1, disclosing a molded three-dimensional plastics geometry adapted to be mounted against a building corner on the exterior side of a wall portion.
The present invention relates however to interior sealing of buildings and more precisely air sealing of building corners with the purpose of creating an airtight vapour retarder/vapour barrier on the interior side of the building for improved energy consumption by reduced energy losses and controlled ventilation.
Massive concrete walls and plastered brick walls largely consist of inorganic material which is not particularly sensitive to moisture. Moreover they are in most cases very airtight and resist moisture very well, and therefore no additional air sealing with a separate vapour barrier or vapour retarder is usually considered necessary.
Other walls such as wood stud walls must be air sealed and protected from moisture. This type of wall in fact largely consists of organic material, such as wood and paper-coated gypsum boards, and is therefore very sensitive to the action of moisture. In order to further prevent damage due to moisture, reduce energy loss and control the ventilation in the building, thus improving the rational use of energy, the stud walls are provided with a diffusion- and airtight inside and a diffusion-open, windproof and rainproof outside. The diffusion and air seal consists of an airtight film with vapour retarder or vapour barrier properties and can be made of, for example, plastic film, aluminium foil, impregnated kraft paper or laminates of these materials. Laminates, if any, can be provided with a reinforcing carrier layer.
In mounting of the diffusion and air sealing film, problems arise, for example, in pipe lead-throughs and in irregularities/recesses in the wall structure, such as in windows and doors.
U.S. Pat. No. 5,243,787 discloses a simple method which is intended for solutions in which the window frame and the wall are positioned in the same plane. The diffusion and air sealing film is, according to the method, first stretched across the window, after which two diagonal cuts are made in the film so that four triangular flaps are formed. These flaps are then folded away from the window portion and fastened to the walls.
In the cases where the window frame and the wall are not positioned in the same plane but instead a window bay is formed, the above solution cannot be used. However, initially the same method as described above is used, that is the diffusion and air sealing film is stretched across the window and two diagonal cuts are made in the film so as to form four triangular flaps. Subsequently these flaps are folded into the window bay and fastened to its walls, after which residual material in the tips of the flaps is removed. In this method, there is however no diffusion and air sealing film in the corners, in the following referred to as building corners, at the basis of the flaps. In some cases, these portions, below referred to as leaks, are left without diffusion seal, resulting in zones that are not tight adjacent the windows with the risk of damage due to moisture, resulting in a great loss of energy. In most cases, these building corners are, however, sealed by means of pieces of diffusion and air sealing film. The leaks in the film that arise in any of these positions are usually sealed with adhesive tape, sealing strip or jointing material and pieces of film. By these building corners being three-dimensional, adhesive tape or sealing strip is attached along and frequently over an edge, which means that the originally two-dimensional tape/strip must be folded to follow the three-dimensional extent. This requires precision and patience and often tends to result in undesirable wrinkling. The greatest problem occurs at the point P at which three surfaces in the building corner coincide and easily several overlapping layers of adhesive tape are required. If the worst comes to the worst, this can result in difficulties in the subsequent mounting of cover panels and surface layers.
Traditionally there have been no guide lines and rules to how air sealing is to take place, which means that this takes place at the fitter's discretion. It is also difficult to inspect the quality of the work since walls, window bays etc are subsequently coated with additional material in the form of, for example, borders, panels, gypsum boards and other facings.
Furthermore, it is nowadays necessary to carry out pressure testing of many buildings, in particular low energy buildings, which are often referred to as “passive houses”. Pressure testing occurs to prove that the seal is sufficient and to track any leaks before mounting panels and other facings. However, suitable air sealing elements to take care of any deficiencies are currently not available.
The above problems are associated not only with windows, but also appear in connection with other components, such as doors.
On the other hand, to prevent damage due to moisture, reduce energy loss and allow controlled ventilation in buildings at an intersection between a wall portion and a beam portion projecting from the wall portion, selected parts such as walls and intermediate floors may be provided with a diffusion and airsealing film.
An intermediate floor is a load-bearing component, which separates the different storeys of a building. The intermediate floor structure comprises a structural part, i.e. beams, floor and ceiling. The main function of the beams forming the structural framework is to carry the load of one storey and transferring the weight of this load onto the load-bearing walls and columns. The load is distributed via the floor structure, which consists of a plurality of beams extending across the building from one outer wall to the other. In the case of the top floor structure of a building, the intermediate floor is formed by roof trusses, which are arranged side by side.
To provide a suitable seal, the floor structure, beams and walls are clad, as stated above, with a diffusion and airsealing film. The cladding is applied before the floors and wall panels are mounted, which means that the film is stretched over the wall portions and the beams, respectively, of the intermediate floor. A consequence of this is that problems arise at the portion of the floor structure where it connects onto the wall, i.e. where each individual beam projects.
At such geometric intersections “patching and mending” is often employed, i.e. the fitter has no choice but to cut the film to the best of his ability and to patch and seal using individually cut pieces of leftover film, tape, sealing strips or jointing compound. Depending on the skill of the fitter, his awareness of the importance of the seal and whether he is pressed for time or not, there is a risk that some portions will not be sealed at all or will be inadequately sealed, which may result in damage due to moisture and considerable energy loss.
Traditionally there has been a lack of guidelines and standard specifications concerning the provision of airtight sealing, which means that the work of the fitter is based on arbitrariness. Furthermore, it is difficult to inspect the quality of the work since the walls and intermediate floor are subsequently clad in additional material in the form of, for example, skirting, panels, plasterboards, floorboards or other cladding.
Moreover, today pressure tests are required for many buildings, in particular for low-energy buildings, which are often referred to as “passive houses”. The purpose of the pressure test is to document that the air tightness is sufficient and to trace any leakage before panels and other surface cladding are mounted.